
/**
 * 
 * @param {Document} elem dom对象 
 * @param {String} obj 
 * @returns String
 */
function setStyle(elem,obj){
    if(Object.prototype.toString.call(obj) != '[object Object]'){
        return;
    }
    for(var key in obj){
       elem.style[key]=obj[key];
    }
    }